1. Field of the Invention
The present invention relates to storage area networks, and more particularly, to managing boot LUNs in a storage area network.
2. Background of the Invention
Storage area networks (“SANs”) are commonly used to store and access data. A SAN is a high-speed sub-network of shared storage devices, for example, disks and tape drives. A computer system (may also be referred to as a “host”) can access data stored in the SAN.
Typical SAN architecture makes storage devices available to all servers that are connected using a computer network, for example, a local area network or a wide area network. The term server in this context means any computing system or device coupled to a network that manages network resources. For example, a file server is a computer and storage device dedicated to storing files. Any user on the network can store files on the server. A print server is a computer that manages one or more printers, and a network server is a computer that manages network traffic. A database server is a computer system that processes database queries.
Various components and standard interfaces are used to move data from host systems to storage devices in a SAN. Fibre Channel is one such standard. Fibre Channel (incorporated herein by reference in its entirety) is an American National Standard Institute (ANSI) set of standards, which provides a serial transmission protocol for storage and network protocols such as HIPPI, SCSI (small computer system interface), IP, ATM and others. Fibre Channel provides an input/output interface to meet the requirements of both channel and network users.
Host systems often communicate with storage systems via a host bus adapter (“HBA”) using the “PCI” bus interface. PCI stands for Peripheral Component Interconnect, a local bus standard that was developed by Intel Corporation®. The PCI standard is incorporated herein by reference in its entirety. PCI is a 64-bit bus and can run at clock speeds of 33 or 66 MHz.
PCI-X is a standard bus (incorporated herein by reference in its entirety) that is compatible with existing PCI cards using the PCI bus. PCI-X improves the data transfer rate of PCI from 132 MBps to as much as 1 GBps. The PCI-X standard was developed by IBM®, Hewlett Packard Corporation® and Compaq Corporation® to increase performance of high bandwidth devices, such as Gigabit Ethernet standard and Fibre Channel Standard, and processors that are part of a cluster.
The iSCSI standard (incorporated herein by reference in its entirety) is based on Small Computer Systems Interface (“SCSI”), which enables host computer systems to perform block data input/output (“I/O”) operations with a variety of peripheral devices including disk and tape devices, optical storage devices, as well as printers and scanners. A traditional SCSI connection between a host system and peripheral device is through parallel cabling and is limited by distance and device support constraints. For storage applications, iSCSI was developed to take advantage of network architectures based on Fibre Channel and Gigabit Ethernet standards. iSCSI leverages the SCSI protocol over established networked infrastructures and defines the means for enabling block storage applications over TCP/IP networks. iSCSI defines mapping of the SCSI protocol with TCP/IP.
The iSCSI architecture is based on a client/server model. Typically, the client is a host system such as a file server that issues a read or write command. The server may be a disk array that responds to the client request. Devices that request I/O processes are called initiators. Targets are devices that perform operations requested by initiators. Each target can accommodate up to a certain number of devices, known as logical units, and each is assigned a Logical Unit Number (LUN). LUN(s) throughout this specification means a logical unit number, which is a unique identifier, on a Parallel SCSI or Fiber Channel or iSCSI target.
Boot LUNs are used to boot servers in a SAN environment. In conventional systems, to boot from a Fibre Channel device, each HBA needs to be configured with the name of the boot device. To configure the HBAs, one has to evaluate each server and store either the port name or port identifier and LUN number of the target device.
Conventional systems manually associate a HBA's worldwide port number (“WWPN”) provided by the HBA manufacturer to a server blade. The WWPN is manually entered for LUN masking. “CTRL Q” utility is used for each blade's WWPN and to identify boot LUNs. Conventional systems are manual and tedious since boot information is not available at a single point.
The problem becomes worse in a cluster environment. In a clustered environment, the system may be required to boot to different operating system partitions on the same blade, i.e., different boot LUNs have to be enabled for the same blade and the boot LUNs need to be protected from each other.
Conventional systems do not provide an efficient methodology to manage boot LUNs and the boot process itself. Therefore, there is a need for a method and system for efficiently managing the boot process in SANs.